Photoluminescent printed waveguides based on lightwave coupling can be produced using various photoluminescent colorants which are transparent when non-energized, yet emit color when subjected to ultra-violet, violet, or blue light energy. By printing on clear waveguides, multiple waveguide layers can be stacked and alternately energized to produce engaging motion effects. This technology has the benefit over competing technologies such as LCD in that it is a low cost printed approach which can be produced in sizes and shapes other than the standard ratio rectangular LCD products. Unlike LCDs, these display systems can also be contour cut or formed into three dimensional shapes. Additionally, by incorporating a back lit or edge lit visible light illuminated graphic behind the photoluminescent layer(s), one can further extend graphic life and the ability to support high color content artwork while maintaining desirable features of low cost and flexible geometry. The extreme of high color content artwork is white whereas the extreme of low color content artwork is black.
Placing an edge lit or back lit visible light illuminated graphic (for example a DURATRANS®) behind the photoluminescent layer(s) has the benefits of long illuminated life and the ability to support up to 100% white content. However, even in the non-illuminated state subjected only to ambient light, these transparencies can exhibit much visible color and therefore may not provide a sufficiently dark background for the photoluminescent layer(s).
Using photoluminescent layers to present imagery in front of one or more physical objects wherein the photoluminescent layers are largely transparent in the non-energized state such that the physical object(s) may be viewed through the photoluminescent layer(s) provides a compelling aesthetic presentation. The physical object(s) can optionally be placed in an enclosed structure such that ambient light is prevented from entry except through the photoluminescent layers. With emissive phosphors, it is impossible to create darkness. Primary RGB colors combine to form white. Therefore, provision of a dark background for image contrast is needed. This background can be provided by a dark ambient background such as in a dimly lit room, or by placing a dark surface behind the photoluminescent printed panels.
In photoluminescent printed waveguides, ultra-violet, violet, or blue excitation light is consumed by the presence of phosphors. The greater the amount of phosphors, the greater the requirement for excitation energy. In practice, producing an emissive display system with high light colored content consumes much more energy than one containing largely dark colored content. This limits the amount of photoluminescent ink which can be excited, and hence restricts the kind of artwork which can be sufficiently energized using this approach.
In waveguide based display systems where a beam angle limited light source is used, light needs to be delivered to the graphic region with useful distribution. To achieve a useful light distribution, some waveguide distance from the light source must be provided to allow the light to spread. This region wherein light is not sufficiently spread increases overall display system size and cost, and generally reduces appeal.
When illuminating a waveguide display system with multiple beam angle limited light sources, the periodicity of the light source placement and beam expansion angle determine the distance into the waveguide where the light will merge with lighting from the adjacent light source. For edge lit systems, this creates a generally undesirable light mixing region wherein some portions of the waveguide have excitation energy and others do not. This region is generally not useful for illuminating graphics. It is often hidden from view behind framing. When designing display systems, one must often include this non-graphic light spreading region which adds to waveguide cost.
Many commercial display system geometries are very long and thin. One such example is the front edge of a store aisle shelf. This is just one example of many relevant examples. In the current art, the required light spreading region is so large as to require a large percentage of the viewable area to be a non-graphic light spreading region to an extent that the result is unappealing. For example, on a 1.5 inch tall shelf strip in the current art, with light sources on half inch centers and a +/−60 degree beam angle, approximately ⅜″ of the waveguide must be non-graphic to allow for light mixing. For these reasons, many thin geometry market opportunities are not viable or sufficiently appealing.
Many non-graphical features in the current art consume valuable visual real estate. For example, the light source height, the light source circuit board, and the supporting frame. Often the supporting frame must include additional geometry for routing wires. Often, illumination sources are provided on more than one edge of a display system, further reducing the visible graphic area. This makes small display systems unattractive since so much of the viewable area is consumed. This also is generally a negative impact on larger display systems as advertisers generally want to maximize use of visible area.
For waveguide based transparent or semi-transparent multi-layer artwork display systems, there is currently much opportunity for installation of individual layers in the incorrect position and orientation. Being transparent or semi-transparent, it is challenging to determine which is the top, bottom, right, left, front, and back for a stack of image layers. As the number of layers increase, the chance for error increases.
In the current art, a significant cost driver for waveguide printed graphics is the cost of the waveguide itself. When printing multi-layer display systems, this cost is multiplied. Any non-graphic waveguide region required for light mixing adds cost over time as graphics are refreshed. For example, for 0.118 inch thick acrylic, the cost per square foot is around $2/square foot. For a 36 inch shelf strip×⅜ inch mixing region×2 layers=40 cents. Over the life of a display system say 4 campaigns/year for 3 years=12 campaigns=$5.40.
In the current art, a large cost and weight driver for waveguide printed graphics is the material thickness.
Light distribution in waveguide based display systems using beam angle limited light sources poses numerous difficulties. If no condensing optics are used, the waveguide must be at least similar in cross sectional height to the light source in order to receive the light. Furthermore, most light sources used in waveguide based display systems have a large beam angle distribution. For example +/−60 degrees is common. Light wave propagation across the waveguide is highly influenced by this angular distribution. The higher the beam angle, the greater the frequency of surface touches. The greater the frequency of surface touches which hit photoluminescent phosphors, the quicker the light energy will be consumed. Incorporating optics to shape the light can improve the distribution of light in the waveguide, and also reduce the required waveguide thickness. However, the effectiveness of such optics is highly related to the optic size. An effective optic can be much larger than the waveguide thickness. Incorporation of such optics directly adjacent to the photoluminescent or visible light waveguide requires additional geometry which can further reduce the visible graphic region. For multi-layer display systems, it is desirable to stack the layers close together. When layers are stacked close to one another, the challenge is further compounded in the stacking direction as sizable optics for shaping light into one layer can interfere with positioning the adjacent layer.
Optics to shape beam angle distributed source light into the edge of a very thin flexible waveguide has some practical limits. As the waveguide thickness is reduced, the need for precision alignment increases and also the required optic geometry size increases. For multi-layer display systems, it is desirable to stack the layers close together. When layers are stacked close to one another, the challenge is further compounded in the stacking direction as sizable optics for shaping light into one layer can interfere with positioning the adjacent layer. Incorporation of such optics directly adjacent to the edge of the photoluminescent or visible light waveguide requires additional geometry which can further reduce the visible graphic region.
In addition to flat display systems, single or multi-layer three dimensional waveguide display systems also may lose valuable graphic viewable area when the source lights are placed directly abutted to the edges of the waveguide. For instance, a curved cylindrical waveguide display system requires a seam beneath which the light sources are hidden.
In addition to rectangular display systems, single or multi-layer non-rectangular waveguide display systems also lose valuable graphic viewable area when the source lights are placed directly abutted to the edges of the waveguide.
When illuminating a waveguide display system with light sources placed directly abutted to the edges of the waveguide, the light source can become directly visible to the observer when not sufficiently hidden behind a feature such as framing. To ensure that direct view of such light sources is avoided, the framing or other obscuring material must extend far enough that the light sources are hidden from observer view. This may require additional geometry which can further reduce the visible graphic region.
An important application is placing one or more transparent or semi-transparent photoluminescent waveguide layer(s) in front of one or more physical objects such that the waveguide layer(s) can present graphics and then become transparent allowing the physical object(s) to be seen. For example, physical product such as a bottle of perfume can be placed behind one or more waveguide layers such that when energized, the waveguide panel presents an illuminated graphic feature, yet which is also capable of allowing the viewer to see through the panel to the bottle of perfume. Another example is for a cooler door. Often the supporting frame must include additional geometry for routing wires. Often, illumination sources are provided on more than one edge of a such waveguide display systems, further reducing the visible graphic area. This makes small display systems unattractive since so much of the viewable area is consumed. This also is generally a negative impact on larger display systems as advertisers generally want to maximize use of visible area.
Therefore, a cost efficient display system is needed to address these fundamental limitations enumerated above.
Therefore, a solution capable of expanding a single light source beam prior to illuminating a graphic region is desirable.
Therefore, a solution capable of mixing multiple periodic light source beams prior to illuminating a graphic region is desirable.
Therefore, a solution capable of supporting single or multi- layered graphic display systems with very thin visible areas is desirable.
Therefore, a solution capable of minimizing non-graphic region display system geometry facing the observer is desirable.
Therefore, a solution capable of receiving a keyed mistake proof multi-panel installation geometry is desirable.
Therefore, a solution capable of minimizing cost of replacement graphics by eliminating the non-graphic light mixing region is desirable.
Therefore, a solution capable of minimizing waveguide thickness is desirable.
Therefore, a solution which enables light shaping optics to be positioned such that they do not reduce the graphic region visible to the observer is desirable.
Therefore, a solution which enables light shaping optics to introduce excitation energy into thin film yet which do not reduce the visible graphic region is desirable.
Therefore, a solution which delivers light to single or multi-layered display system which is not flat (curved or thermoformed) is desirable.
Therefore, a solution which introduces light into a waveguide based single or multi-layered contour cut display system is desirable.
Therefore, a solution which eliminates visibility of the source lights from view is desirable.
Therefore, a solution capable of minimizing non-graphic region display system geometry facing the observer when placing single or multi-layer transparent or semi-transparent photoluminescent waveguide panels in front of one or more physical objects is desirable.